Several techniques have been used to improve the cytocompatibility of polymer surfaces by chemical or physical techniques for tissue engineering applications. For example, polyurethane (PU) and poly-lactic co-glycolic acid (PLGA} surfaces can be nanostructured by etching a polymer surface with solutions of HNO3 and NaOH, respectively. Thapa, A, et al., Biomaterials (2003) 24:2915-2926; and Thapa, A, et al., J. Biomed. Mater. Res. (2003) 67A:1374-1383. Nanostructuring of polymer surfaces can improve cell adhesion and proliferation. Additional methods of nanostructuring polymer surfaces include electron beam lithography, mechanical brushing (e.g., U.S. Pat. No. 7,838,074), nanopatterning the surface of a metal mold (e.g., U.S. Pat. No. 8,168,076), ion beam etching, reactive ion etching, plasma etching, and plasma assisted chemical vapor deposition (PACVD) (e.g., U.S. Pat. No. 8,486,280).
Medical devices that are surgically implanted are subject to bacterial growth and biofilm formation on their outer surfaces, which often results in serious infections and the need to surgically remove or replace the device. Previous efforts to inhibit the growth of bacteria on such surfaces include chemical modification of the polymer surface (e.g., U.S. Pat. No. 4,001,432), and the application of coatings containing antimicrobial materials such as silver (e.g., U.S. Pat. No. 8,192,765). However, such methods remain subject to variability, poor durability, and potential toxicity.
Thus, there remains a need to develop new methods of nanostructuring polymer surfaces used in implantable medical devices and developing surfaces that resist bacterial adhesion and biofilm formation.